Process of toxicity induction



July 28, 1942. 1, E, HARVEY, JR 2,291,301

Pnocss oF ToxIcITY INDUCTION Filed Aug. 14, 1940 #ya/1:05am 770/1/ CHA/:155e fox/0E CAT/u xsf) Siwa/nlm@ I Patented July 28, 1942 PROCESS F TOXICITY INDUCTION Jacquelin E. Harvey, Jr., Atlanta, Ga., assignor of one-half to Southern Wood Preserving Company, East Point, Ga., acorporation of Georgia Application August 14, 1940, Serial No. 352,662

2 Claims. (Cl. 19653) The present invention relates to the process of toxicity induction.

More specifically the present invention relates to the induction of toxicity in tars or fractions thereof of aromatic content.

An object of the present invention is the induction of toxicity in hydrocarbons having little or no toxicity, and of increasing toxicity in hydrocarbons having toxicity.

Another object of the invention is the improving of toxic value in wood preserving oils of current manufacture; the improving of toxic properties in the parent materials of wood preserving distillates of current manufacture; and the improving of toxic properties in residual materials resulting from the distillation recovery of wood preserving oils from tars or the like.

Another object of the present invention is the lowering of sulphur content in the starting materials, whereby, among other things, to reduce corrosivity in the finished product of enhanced toxic value.

Another object of the present invention is the controlling of reaction conditions so as to induce no substantial percentage of liquid chain structures or other liquid materials that lower toxicity, or make induction of toxicity impossible.

Other objects of the present invention will be apparent from the following disclosures.

The invention will be understood from the following description of illustrative steps comprising various methods of securing the objects of the invention, when read in connection with the accompanying drawing wherein the gure is a diagrammatic sketch of an apparatus for carrying out a form of the process of the invention and wherein the nature of the step carried out in each chamber and the contents thereof are indicated by legend.

Example 1.-A sulphur-bearing coal tar creosote of known toxic value and having a specific gravity of substantially 1.08, a coke residue of substantially 2% and substantially 35% residue above 355 C. is treated with hydrogen at a temperature of 350 C. and a pressure of 200 atmospheres; the thus treated coal tar creosote will be found upon inspection to have reduced corrosivity which advantage will pass to the finally processed material. The coal tar creosote of reduced sulphur content is passed through a high pressure reaction chamber while simultaneously flowing hydrogen therewith at a temperature of 400 C. and a pressure of 200 atmospheres. The catalyst is molybdenum oxide, and the ow of hydrogen 11,000 cubi-c feet per barrel feed stock and the time of reaction thirty minutes. The beneciated creosote flowing from the reactor is inspected and found to have increased toxic Value as stemming from reduced coke residue, specic gravity and viscosity; it will be found that there had been induced no substantial percentage of liquid chain structures or other liquid materials that precluded the induction of toxicity. The final product will be found to have a lowered corrosivity as compared to the starting material.

Example 2.-A sulphur containing coal tar, specific gravity 1.1641 and substantially above 10% coke residue is treated with hydrogen at a temperature of 325 C. and a pressure of 200 atmospheres; the thus treated coal tar will be found upon inspection to have reduced corrosivity which will pass to the finally processed material. The coal tar of reduced sulphur content is passed through a high pressure reaction chamber while simultaneously flowing hydrogen therewith at a temperature of 395 C. and a pressure of 200 atmospheres while contacting a tungsten oxide catalyst. The flow of hydrogen is 12,000 cubic feet per barrel feed stock and the time of reaction forty-ve minutes.

The beneficiated coal tar iiowing from the reactor is inspected and found to have increased toxic value as stemming from reduced coke residue, specific gravity, and viscosity, and the fact that no substantial percentage of liquid chain structures or kindred materials had been induced as to make added toxicity impossible. The final product will have a lowered corrosivity as compared to the starting material.

Example 3.-A sulphur-bearing coal tar fraction Whose initial boiling point is substantially 230 C. and characterized by content of high molecular complexes is treated with hydrogen at a pressure of 200 atmospheres and 350 C. temperature. The thus treated coal tar fraction will be found upon inspection to have reduced corrosivity which will pass to the nally processed material. The coal tar fraction of reduced sulphur content is subjected to the action of a flow of hydrogen in a presence of a molybdenum oxide catalyst VWhile passing said tar fraction through a high pressure reaction chamber at a temperature of 400 C. and a pressure of 300 atmospheres. The flow of hydrogen is 15,000 cubic feet per barrel feed stock and the reaction period forty-ve minutes.

The beneciated coal tar fraction flowing from the reactor is inspected and found to have increased toxic value as stemming from, among other things, reduced coke residue, specific gravtemperatures and pressures may be chosen with- V in a wide range inasmuch as sulphur reduction occurs at lowered temperatures and pressures. The lower limit of temperature and pressure-is advisably that temperature and pressure'w'hich effects the reduction in a commercial manner,"as

regards the time element; pressures .as high as practicable may be used, and the upper limit of temperature is dened as that temperature which causes, under condition of the process, no substantial deposition of carbon, as for instance coking.

The step characterized by reduction of corrosivity may be carried on in a high pressure bomb or in a continuous manner in a reaction chamber or several reaction chambers, and in the event of continuous practice, the hydrogen ow is preferably maintained so as to induce no substantial carbon deposit, as for instance coking.

In the second cycle of hydrogen action, ows of hydrogen in the order of 8,000-15,000 cubic feet per barrel feed have proven satisfactory, however, higher or lower flows may be used, the high and low limits thereof being defined as those flows that induce undesirable coking.

By the term beneciated as used herein and in the appended claims is meant the starting material at least once subjected to the action of hydrogen in accordance with the present invention.

Starting materials consist of tars of aromatic content and fractions thereof, characterized by sulphur content and capable of having toxicity induced therein.

The present invention is predicated on, among other things, controlling hydrogen action in both cycles so that no substantial percentage of liquid chain structures or kindred materials are induced that would preclude toxicity induction.

Hydrogen action is also controlled so that no substantial percentage of the starting material is converted to coke.

The second cycle of hydrogen action may be practiced at lowered pressure and temperature; however, pressures of in the order of 200-400 atmospheres are preferred but higher or lower pressure may be used. Temperatures of in excess of 300 C. are preferred, however, lower temperatures may be used, the upper liimt of usable temperatures are dened by those temperatures which cause no inordinate coking action.

Some of the starting materials in which toxicity may be induced in accordance with the present invention may contain high molecular complexes that are especially susceptible to thermal degradation; these materials may have toxicity induced therein while higher pressures obtainwith the added benet that said molecular complexes are reduced to a greater extent, thus enhancing toxicity induction.

By the term molecular complexes is meant to designate those high boiling fractions of tars of aromatic content that are susceptible to thermal degradation, as for instance those high boiling fractions that may be viewed as ring multiplicities.

The time element yof the present invention in the second cycle of hydrogen is not -circumscribed by any definite time limit, but is merely that period necessary to show toxicity enhancement; using some starting feeds periods of thirty minutes or less will result in enhanced toxicity. Periods of one hour or more may be used.

In the rst cycle of hydrogen action that reduces sulphur content, said reduction of sulphur may beV accomplished in the presence of a catalyst. Catalysts effective in the presence of hydrogen are usable, as for instance, the oxides .and/or sulfides of molybdenum, vanadium, uranium, cobalt, tin, manganese, tungsten, or the like.

Starting materials previously subjected to the action of hydrogen are suitable starting mateials. H

When reference is made to high molecular complexes contained in the starting material, and when the starting material contains low boiling fractions that are not considered high molecular complexes, it is of course obvious that the high molecular complexes contained in the starting material are to a certain extentfdepolymerized by the solvent present. Y

Starting materials of the present process also include tars of aromatic content from which low boiling fractions have been removed, as forA instance, tars from which solvent oils have been removed. Viewed broadly, the starting materials of the present process are tars of aromatic content, fractions of said tar more viscous than the starting material due to removal of low boiling `fractions from the starting materiaL-high boiling fractions and pitches.

The term pitch as used herein includes the higher boiling fractions of tars, in --other words tars from which low boiling endsl have been stripped, such low boiling ends being suitable for 'use per se as creosote, other wood preservative or solvent. For instance, the nal residue resulting from evaporating tar `to dryness and then stripping wood preservative from the distillate is a very suitable pitch for use as a starting material of the present process. Y

It will be seen that by reduction of sulfur content of the material under treatment during any stage of hydrogen action, the oxide catalyst used during subsequent stages is at least partially protected from the effect of the sulfur. Y

Minor changes within the scope of the appended claims may be made without departing from the spirit of the invention.

I claim:

1. In the induction of toxicity the process which comprises: subjecting a sulfur-bearing mixture of high temperature coal tar fractions to the action of hydrogen whereby to reduce sulfur content; thereafter subjecting said sulfur-refined material to the Vaction of a flow of hydrogen in excess of 2,000 cubic feet per bar- Vrel feed stockY at a pressure in excess of 50 atmospheres and a temperature in excess of 250 C. while contacting an oxide catalyst whereby to reduce coke residue, specic'gravity and viscosity;

carrying. on the process with conditions so con- 2. In the induction of toxicity the process which comprises: subjecting a sulfur-bearing mixture of high temperature coal tar fractions to the sulfur reducing eiect of a oW of hydrogen at a temperature not substantially less than 325 C. and a pressure at least in the order of 200 atmospheres; thereafter subjecting said sulfur rened material to the action of a ow of hydrogen not substantially less than 11,000 cubic feet per barrel feed stock in the presence of an 0X- ide catalyst at a temperature and pressure not substantially less than 400 C. and 200 atmospheres, respectively, whereby to provide a beneciated material having toxicity in excess of the original feed stock.

JACQUELIN E. HARVEY, JR. 

